Many electrical connector applications require the use of hermetically sealed connectors, i.e., connectors having a hermetic seal between the one or more electrical contacts of the connectors and the panel or other support member through which the contacts extend. One important application for hermetically sealed connectors is in interface connectors for high-voltage applications. The hermetic seal must be maintained through many cycles of high and low temperature during in-service use, necessitating the use of diverse materials which must have about the same coefficient of thermal expansion.
Known hermetically sealed interface connectors may comprise a plastic tubular housing including an integrally molded transverse wafer having a plurality of contact pins extending through and supported within a plurality of apertures in the wafer. Generally, interface connectors are mounted to an outer metallic housing or can, and with this type of plastic connector it was necessary to attach such as by insert molding techniques a separate metal flange around the plastic housing to provide for mechanical connection to the can. An example of such a prior art plastic interface connector is disclosed in U.S. Pat. No. 3,522,575. One feature disclosed in this reference is the use of flanges or recesses along the portion of the contact embedded in the plastic, which provides an elongated length along which a path would have to be opened to result in leaks, and which provides a greater bonding surface; the reference also discloses a particular technique for enhancing the bond between the contact and the plastic.
Another known type of interface connector utilizes a housing of an electrically conductive metal such as KOVAR iron/nickel/cobalt alloy (trademark of Carpenter Technology Corporation) in which the housing can be directly soldered to the can along an integral flange portion, avoiding the necessity of a separate metal flange. In interface connectors incorporating metal wafers, the individual contact pins were retained within apertures in the transverse metal wafer by glass or ceramic plugs which supported the contacts and provided a hermetic seal between the contacts and the side walls of the apertures.
Glass plugs provide a reliable hermetic seal. The type of glass such as borosilicate, and the type of metal such as KOVAR, however, are relatively expensive materials; and manufacture of connectors with glass plugs requires the attainment of very high temperatures in several stages of manufacture: to decarburize or drive off carbon from the metal; to form a thick enough oxide layer on the metal; and to melt the glass preform in the plate aperture and about the contact to form a hermetic seal with the oxide layer.